Routine diagnostics for neural antibodies,clinical correlates,treatment and functional outcome

Objective

To determine frequencies, interlaboratory reproducibility, clinical ratings, and prognostic implications of neural antibodies in a routine laboratory setting in patients with suspected neuropsychiatric autoimmune conditions.

Methods

Earliest available samples from 10,919 patients were tested for a broad panel of neural antibodies. Sera that reacted with leucine-rich glioma-inactivated protein 1 (LGI1), contactin-associated protein-2 (CASPR2), or the voltage-gated potassium channel (VGKC) complex were retested for LGI1 and CASPR2 antibodies by another laboratory. Physicians in charge of patients with positive antibody results retrospectively reported on clinical, treatment, and outcome parameters.

Results

Positive results were obtained for 576 patients (5.3%). Median disease duration was 6 months (interquartile range 0.6–46 months). In most patients, antibodies were detected both in CSF and serum. However, in 16 (28%) patients with N-methyl-d-aspartate receptor (NMDAR) antibodies, this diagnosis could be made only in cerebrospinal fluid (CSF). The two laboratories agreed largely on LGI1 and CASPR2 antibody diagnoses (κ = 0.95). The clinicians (413 responses, 71.7%) rated two-thirds of the antibody-positive patients as autoimmune. Antibodies against the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), NMDAR (CSF or high serum titer), γ-aminobutyric acid-B receptor (GABABR), and LGI1 had ≥ 90% positive ratings, whereas antibodies against the glycine receptor, VGKC complex, or otherwise unspecified neuropil had ≤ 40% positive ratings. Of the patients with surface antibodies, 64% improved after ≥ 3 months, mostly with ≥ 1 immunotherapy intervention.

Conclusions

This novel approach starting from routine diagnostics in a dedicated laboratory provides reliable and useful results with therapeutic implications. Counseling should consider clinical presentation, demographic features, and antibody titers of the individual patient.

     

A role for cannabinoids in the treatment of myotonia? Report of compassionate use in a small cohort of patients

Journal of Neurology - The symptomatic treatment of myotonia and myalgia in patients with dystrophic and non-dystrophic myotonias is often not satisfactory. Some patients anecdotally report...     

J‐curve association between alcohol intake and varicose veins in Japan: The Shimane CoHRE Study

The effect of alcohol intake on varicose veins (VV) has not been determined by its consumption level. The aim of this study was to investigate the association between alcohol intake and VV in an elderly general population. Using a cross‐sectional approach, the Shimane CoHRE Study data, comprising a total of 1060 participants, were analyzed. By multivariate regression analysis adjusted with basic characteristics, past work history, lifestyle‐related factors and medical history, compared with non‐drinkers, mild drinkers (<20.0 g/day) showed a significantly lower adjusted odds ratio (aOR) of VV (aOR = 0.64, P = 0.036). In a similar way, regular drinkers (1–5 days/week) showed a significantly lower aOR of VV when compared with occasional drinkers (aOR = 0.57, P = 0.032). VV and alcohol intake showed J‐curve relationships. In a stratified analysis by alcohol consumption levels, the association of smoking and VV were also observed in moderate to heavy drinkers and habitual drinkers. These findings can provide better understanding of pathophysiological mechanism and be used for evidence‐based patient education.     

Physical activity levels and perceived benefits and barriers to physical activity in HIV-infected women living in the deep south of the United States†

Engaging in regular physical activity (PA) is important in maintaining health and increasing the overall quality of life of people living with HIV (PLWH). The deep south of the USA is known for its high rate of sedentary behavior although data on the activity levels and perceptions of the benefits and barriers to exercise in women living with HIV in the deep south are lacking. Understanding the perceived benefits and barriers to exercise can guide the development of PA interventions. We conducted a cross-sectional study to determine the PA levels and perceived benefits and barriers to exercise associated with both age and depression level in a group of HIV+ women living in the deep south. We recruited a total of 50 participants from a cohort site for the Women’s Interagency HIV Study. Depression was assessed using the Center for Epidemiological Studies Depression Scale (CES-D) and benefits/barriers to exercise were measured using the Exercise Benefits and Barriers Scale (EBBS). We measured PA both subjectively and objectively using the International Physical Activity Questionnaire (IPAQ) and a Fitbit PA monitor, respectively. Our sample was predominantly African-American (96%) and the mean ±SD age, body mass index, and CES-D score were 42?±?8.8 years, 36.6?±?11.5?kg/m², and 15.6?±?11.4, respectively. Both subjective and objective measures of PA indicated that our participants were sedentary. The greatest perceived benefit to exercise was physical performance and the greatest barrier to exercise was physical exertion. Higher overall perceived benefits were reported by women ≥43 years and women reporting higher levels of depression. There was no difference in overall barriers associated with age and depression level, but women with depression felt more fatigued by exercise. The results of this study can be helpful when designing and implementing PA interventions in women living with HIV in the deep south.     

Naphthylphthalamic acid associates with and inhibits PIN auxin transporters

N-1-naphthylphthalamic acid (NPA) is a key inhibitor of directional (polar) transport of the hormone auxin in plants. For decades, it has been a pivotal tool in elucidating the unique polar auxin transport-based processes underlying plant growth and development. Its exact mode of action has long been sought after and is still being debated, with prevailing mechanistic schemes describing only indirect connections between NPA and the main transporters responsible for directional transport, namely PIN auxin exporters. Here we present data supporting a model in which NPA associates with PINs in a more direct manner than hitherto postulated. We show that NPA inhibits PIN activity in a heterologous oocyte system and that expression of NPA-sensitive PINs in plant, yeast, and oocyte membranes leads to specific saturable NPA binding. We thus propose that PINs are a bona fide NPA target. This offers a straightforward molecular basis for NPA inhibition of PIN-dependent auxin transport and a logical parsimonious explanation for the known physiological effects of NPA on plant growth, as well as an alternative hypothesis to interpret past and future results. We also introduce PIN dimerization and describe an effect of NPA on this, suggesting that NPA binding could be exploited to gain insights into structural aspects of PINs related to their transport mechanism.

Many aspects of plant growth are controlled by the hormone auxin. A distinct feature of auxin is that its hormonal action requires it to be actively transported between cells and ultimately throughout the whole plant in a controlled directional or polarized manner, a process known as polar auxin transport (PAT). The ability of plants to perform PAT is ascribed to the auxin export activity of PIN transporters (1). Plasma membrane PINs can be restricted to a specific side of cells (2), and when this polarity is maintained in continuous plant cell files, the combined activity of identically localized PINs results in auxin flowing in that direction (3). This lays the vectorial foundations for PAT to create local auxin gradients and plant-wide PAT streams that are critical for auxin action and normal plant growth (4, 5).Synthetic PAT inhibitors such as N-1-naphthylphthalamic acid (NPA) were initially developed as herbicides and then subsequently exploited by researchers to identify and characterize the unique PAT-based mechanisms that drive plant development (6). Having been used for over six decades, the question as to how NPA actually inhibits PAT has been keenly pursued. Several putative modes of action have been proposed, but the topic remains to date not fully or satisfactorily resolved (6).Early studies established NPA binding with high affinity to membrane-integral components of plant membranes (7–10). With the later discovery of pin1 mutants bearing their distinct bare inflorescences reminiscent of NPA-treated plants (11), followed by identification of the PIN gene family and gradual confirmation that PINs were NPA-sensitive auxin transporters that mediated PAT (1–5), it was apparent that the physiological and genetic evidence overwhelmingly linked NPA to inhibition of PIN activity (6). However, direct molecular association of NPA with PINs has never been reported (6). Instead, a substantial body of data has accumulated suggesting that the NPA target is not PIN itself, but rather other proteins or complexes that either actively coparticipate in PAT or are indirectly involved in control of PAT components (6, 12). Members of the B-family of ABC transporters, such as ABCB1 and ABCB19, showed high-affinity NPA binding and NPA-sensitive auxin export (1, 12–15), thus leading to proposals that they may either physically interact with PINs, or functionally interact such that their nonpolar auxin export activity contributes to PAT and/or to regulation of PINs (12, 16). In these scenarios, PIN/PAT would be rendered vulnerable to the NPA sensitivity of ABCB. However, these schemes are not yet fully resolved, are not fully consistent with key genetic and physiological data (6), and are particularly obfuscated by ABCB1/19 functioning both interactively and independently from PINs (1, 12, 15–20), with ABCB-PIN interaction occurring in an as-yet-unclarified manner (15, 18).A further twist in assigning ABCBs as the main NPA target is their regulation by their chaperone TWD1/FKBP42 (14, 16), with TWD1 itself also being an NPA-binding protein (14, 17). NPA interferes with this regulation and affects TWD1-ABCB interaction, but curiously NPA cannot bind stably to the ABCB-TWD1 complex (14, 17). As TWD1 has also been implicated in NPA-sensitive actin-based PIN trafficking (17), this has led to a model proposing that TWD1 could mediate the NPA sensitivities of both ABCB and PINs, thus presenting TWD1 as a modulator of PAT (17, 21). In an analogous scheme in some plant species, CYPA immunophilins such as tomato DGT, which are functionally similar to TWD1/FKBP42, are suggested to replace TWD1 in modulating auxin transporters and transducing NPA effects to PINs (12, 21).Similar to TWD1, BIG/TIR3 has also been associated with NPA and PIN trafficking (22). Given the undisputed role of trafficking in controlling PIN polarity (5), these reported effects warrant attention, although they are inconsistent with other reports that NPA perturbs neither vesicular trafficking nor actin dynamics in conditions where auxin transport is inhibited (23, 24). Together with trafficking, phosphorylation is another key modulator of PIN polarity as well as activity (5), so it is not surprising to find hypotheses suggesting that NPA could interfere with critical phosphorylation events (6), particularly as PID, a kinase crucial for PIN trafficking and activation, has also been connected to ABCB function and TWD1/ABCB/NPA interactions (25). Others propose that NPA may mimic natural compounds in their capacity as endogenous regulators of PAT, with plant flavonoids being suspected candidates (6, 26). Since flavonoids can compete with or inhibit ATP-binding in mammalian kinases and ABC transporters (27, 28), and as flavonoids can bind to and inhibit PID (25), a phosphorylation-based NPA mode of action would overlap with this hypothesis and poses the question whether NPA acts similarly as an ATP mimic.With these many potential NPA-affected pathways, there is a need to distinguish between low- and high-affinity NPA targets and possible secondary effects due to prolonged PAT inhibition. Current consensus is that low concentrations of NPA (<10 µM) cause direct inhibition of auxin transporters in PAT (21) and the consequent physiological effects seen in planta (IC₅₀ 0.1 to 10 µM) (7, 9, 19, 23, 29). This is associated with high-affinity binding to membranes (K_d 0.01 to 0.1 µM) (7, 8) and the inhibition of PIN/ABCB activity in short-term auxin transport assays (1, 14, 18, 20, 23). In contrast, NPA is thought to affect trafficking (21, 30) and other non-PAT processes (31) when used at higher doses (50 to 200 µM NPA), presumably via binding to its lower-affinity targets, although excessive NPA exposure may also have fast-acting toxic side effects (23). As the in vitro affinity of TWD1 for NPA is surprisingly low (K_d ∼100 µM) (17), the TWD1-mediated NPA effects on PIN/PAT are thought to be of the low-affinity type and linked to trafficking perturbations (17, 21). However, as NPA is always externally applied to plants or cells, it is not clear how or where the drug distributes or accumulates, and thus there may be discrepancies between actual and reported/apparent effective concentrations, as might be the case for TWD1 (17). Finally, NPA also binds with low affinity to inhibit APM1, an aminopeptidase implicated in auxin-related plant growth, but as with trafficking effects, this low-affinity NPA interaction is not connected to direct regulation of PAT (31).Thus, the available data proffer various indirect mechanisms that could lead to NPA inhibition of PIN-mediated PAT, but the proposed schemes have complicating aspects and struggle at times to satisfactorily explain the prime effects of NPA. Here we propose an alternative simpler scenario involving a more direct link between NPA and PINs that would resolve some of these currently outstanding issues. We present evidence from heterologous transport assays, classical in situ membrane binding, and oligomerization studies which collectively suggest that NPA can interact directly in a high-affinity manner with PINs, leading to conformational or structural effects and inhibition of auxin export activity.